The association between embryos of the spotted salamander ( Ambystoma maculatum ) and green algae (“ Oophila amblystomatis ” Lamber ex Printz) has been considered an ectosymbiotic mutualism. We show here, however, that this symbiosis is more intimate than previously reported. A combination imaging algal 18S rDNA amplification reveals invasion embryonic tissues cells during development. Algal are detectable from larval Stages 26–44 through chlorophyll autofluorescence amplification. cell...

•A set of germline transgenic axolotls for spatiotemporal control gene expression•Controlled expression in cartilage and neural stem cells via Cre/loxP system•p16INK4a represses spinal cord regeneration induces phenotype The salamander is the only tetrapod that regenerates complex body structures throughout life. Deciphering underlying molecular processes fundamental regenerative medicine developmental biology, but model organism had limited tools analysis. We describe a comprehensive...

Egg masses of the yellow-spotted salamander Ambystoma maculatum form an association with green alga "Oophila amblystomatis" (Lambert ex Wille), which, in addition to growing within individual egg capsules, has recently been reported invade embryonic tissues and cells. The binomial O. amblystomatis refers algae that occur A. but it is unknown whether this population symbionts constitutes one or several different algal taxa. Moreover, across geographic range maculatum, other amphibians,...

During embryonic development, cells of the green alga Oophila amblystomatis enter salamander Ambystoma maculatum forming an endosymbiosis. Here, using de novo dual-RNA seq, we compared host that harbored intracellular algae to those without and inside animal in egg capsule. This two-by-two-way analysis revealed exhibit hallmarks cellular stress undergo a striking metabolic shift from oxidative metabolism fermentation. Culturing experiments with showed glutamine may be utilized by algal...

Symbiosis is a commonly occurring phenomenon, with most plants and animals being holobionts, comprising of host its corresponding symbionts. It is, however, less common to have symbiont only under specific life stage even more so between photosynthesizing organism vertebrate animal. One such relationship found the unicellular green algae Oophila amblystomatis North American yellow‐spotted salamander Ambystoma maculatum , which far known endosymbiotic an alga vertebrate. In this study we...

Abstract Direct development has evolved in rhacophorine frogs independently from other anuran lineages, thereby offering an opportunity to assess features associated with this derived life history. Using a developmental series of the direct‐developing Philautus silus (Ranidae: Rhacophorinae) Sri Lanka, we examine cranial morphology that are part suite adaptations facilitate feeding free‐living tadpoles, but have been changed or lost lineages. Larval‐specific upper jaw cartilages, which...

Abstract The vertebrate transcription factor protein Runx2 is regarded as a “master regulator” of bone formation due to the dramatic loss osseous skeleton in mouse homozygous knockout. However, mRNA also expressed pre‐hypertrophic cartilaginous and chicken, where its developmental function largely unknown. Several tiers regulation exist mouse, any which may account for seeming biological inactivity during early stages skeletogenesis. Unlike zebrafish require cartilage differentiation....

Recent molecular phylogenies suggest the surprising reacquisition of posthatching metamorphosis within an otherwise direct-developing clade lungless salamanders (family Plethodontidae). Metamorphosis was long regarded as plesiomorphic for plethodontids, yet genus Desmognathus, which primarily includes metamorphosing species, is now nested a much larger species. The extent to putative in Desmognathus represents true evolutionary reversal contingent upon both larva-specific features and were...

SUMMARY Genetic and developmental alterations associated with the evolution of amphibian direct development remain largely unexplored. Specifically, little is known underlying expression skeletal regulatory genes, which may reveal early modifications to cranial ontogeny in direct‐developing species. We describe patterns three key regulators ( runx2, sox9 , bmp4 ) along cartilage‐dominant collagen 2α1 gene col2a1 during anuran, Eleutherodactylus coqui . Expression these transient skeletogenic...

The reorganization of cranial cartilages during tadpole metamorphosis is a set complex processes. fates larval cartilage-forming cells (chondrocytes) and sources adult chondrocytes are largely unknown. Individual may either degenerate or remodel, while many appear to form de novo metamorphosis. Determining the extent which chondrocytes/cartilages derived from requires new techniques in chondrocyte lineage tracing. We have developed two transgenic systems label cartilage throughout body with...

SUMMARY The vertebrate limb demonstrates remarkable similarity in basic organization across phylogenetically disparate groups. To gain further insight into how this morphological is maintained different developmental contexts, we explored the molecular anatomy of size‐reduced embryos Puerto Rican coquí frog, E leutherodactylus coqui . This animal direct development, a life‐history strategy marked by rapid progression from egg to adult and absence free‐living, aquatic larva. Nonetheless,...

Tadpoles of the monotypic Indian dancing frog family Micrixalidae have remained obscure for over 125 years. Here we report discovery elusive tadpoles Micrixalus herrei from sand beds a forested stream in southern Western Ghats, and confirm their identity through DNA barcoding. These actively burrowing lead an entirely fossorial life eggs to late metamorphic stages. We describe internal external morphological characters while highlighting following features: eel-like appearance, extensively...

A unique symbiosis occurs between embryos of the spotted salamander (Ambystoma maculatum) and a green alga (Oophila amblystomatis). Unlike most vertebrate host-symbiont relationships, which are ectosymbiotic, A. maculatum exhibits both an ecto- endo-symbiosis, where some algal cells living inside egg capsules enter embryonic tissues as well individual cells. Past research has consistently categorized this mutualism, making first example "beneficial" microbe entering Another closely related...

The unique symbiosis between a vertebrate salamander, Ambystoma maculatum, and unicellular green alga, Oophila amblystomatis, involves multiple modes of interaction. These include an ectosymbiotic interaction where the alga colonizes egg capsule, intracellular enters tissues cells salamander. One common in mutualist photosymbioses is transfer photosynthate from algal symbiont to host animal. In A. maculatum-O. amblystomatis interaction, there conflicting evidence regarding whether algae...

Abstract This work presents a refined staging table for the direct‐developing red‐backed salamander Plethodon cinereus , which is based on incomplete system of James Norman Dent (J Morphol 1942; 71:577–601). common species from eastern North America member species‐rich lungless family Plethodontidae. The presented here covers several stages omitted by and reveals novel developmental features P. embryos. These include putative Leydig cells open gill clefts, are found in larvae metamorphosing...

The neural crest is a multipotent population of cells that originates variety cell types. Many animal models are used to study induction, migration and differentiation, with amphibians birds being the most widely systems. A major technological advance development in mouse, chick zebrafish has been generation transgenic animals which specific enhancers/promoters drive expression either fluorescent proteins for use as lineage tracers, or modified genes functional studies. Unfortunately, no...

Summary The neural crest (NC) multipotent progenitor cells form at the plate border and migrate to diverse locations in embryo differentiate into many cell types. NC is specified by several embryonic pathways, however role of noncanonical Wnt signaling this process remains poorly defined. Daam1 a formin family protein that present ectoderm time formation can mediate signaling. Our interference experiments indicated required for gene activation. To further study function development we used...

SUMMARY The growing field of skeletal developmental biology provides new molecular markers for the cellular precursors cartilage and bone. These enable resolution early features development that are otherwise undetectable through conventional staining techniques. This study investigates mRNA distributions regulators runx2 sox9 along with cartilage‐dominant collagen 2 α 1 (col2a1) in embryonic limbs direct‐developing anuran, Eleutherodactylus coqui . To date, these genes limb have only been...

This study characterizes regulatory elements of collagen 2 alpha 1 (col2a1) in Xenopus that enable transgene expression cartilage-forming chondrocytes. The reporters described this drive strong cartilage-specific gene expression, which will be a valuable tool for further investigations skeletal development. While endogenous col2a1 mRNA is expressed many embryonic tissues, its becomes restricted to tadpole and adult chondrocyte-specific recapitulated by reporter constructs, were tested...

Abstract This study examines the skeletons of giant non‐metamorphosing (GNM) Xenopus laevis tadpoles, which arrest their development indefinitely before metamorphosis, and grow to excessively large sizes in absence detectable thyroid glands. Cartilage growth is isometric; however, chondrocyte size smaller GNM tadpoles than controls. Most cartilages stain weakly with alcian blue, several are calcified (unlike controls). However, subjacent periosteum‐derived bone retain strong affinities for...

The Indian Purple frog, Nasikabatrachus sahyadrensis, occupies a basal phylogenetic position among neobatrachian anurans and has very unusual life history. Tadpoles have large ventral oral sucker, which they use to cling rocks in torrents, whereas metamorphs possess adaptations for underground. developmental changes that underlie these shifts habits habitats, especially the internal remodeling of cranial postcranial skeleton, are unknown. Using nearly complete metamorphic series from...

Green algae usually assigned to the genus Oophila are known colonize egg capsules of amphibian masses across Nearctic and Palearctic regions. We study phylogenetic relationships these using a phylotranscriptomic data set 76 protein-coding single-copy nuclear genes. Our includes novel RNAseq for six amphibian-associated five free-living green algae, draft genomes two latter. Within clade (nested within Moewusinia), we find samples from European frogs (Rana dalmatina R. temporaria) closely...